St. Lawrence Estuary
The St. Lawrence Estuary is one of the world’s largest estuaries. Some 500 miles (800 km) long, it discharges about 3 million gallons (12 million liters) of water into the Gulf of St. Lawrence each second. The estuary is rich in marine life. In its wide middle and lower reaches, the icy Labrador Current flows 1,000 ft (300 m) below the surface in the opposite direction of the main estuarine flow. In one section, near the mouth of a fjord that branches off the St. Lawrence Estuary, the current’s nutrient-rich waters rise abruptly and mix with warmer waters above. This upwelling of nutrients encourages plankton growth, providing the base of a food chain that involves many species of fish and birds, and a small population of beluga whales.